An example of a surface to be cooled that rotates about a rotation axis and that faces the rotation axis is a surface of an electronic device that becomes hot, said electronic device supplying electrical power to the X-ray source of a computer tomograph and rotating together with the X-ray source about a tube designed to accommodate a patient to be examined. Such a system is also known as a “gantry”.
With a computer tomograph of this type, it is desirable to achieve the highest possible rotational frequency, since on the one hand this enables the number of tomography examinations performed per time unit to be increased and on the other images of fast-moving organs (e.g. the heart) are possible free of artifacts.
The limiting variable for the maximum achievable rotational frequency is the total mass that is to be brought into rotation, which includes, inter alia, not only the X-ray detector but also the mass of the X-ray source, the mass of the device for supplying electrical power to the X-ray source and the mass of a device co-rotating with the X-ray source and serving to cool a surface of the device for supplying the electrical power, said surface becoming hot. The smaller this total mass is, the greater is the maximum achievable rotational frequency. At the same time the rotation radius can be reduced by reducing the size of components, resulting in an overall reduction in the centrifugal force.
A reduction of each individual mass contributing to the total mass in itself causes a reduction in the total mass, as does a reduction in the mass of the device for cooling a surface of the device that becomes hot, said device supplying electrical power to the X-ray source.